The present invention relates to a fly-cutter milling machine for the simultaneous milling of a plurality of profiled structures developed in the form of grooves, surfaces or the like in rotating workpieces (7) by means of a fly cutter (10) which protrudes radially outwards on a rotating tool holder and which plunges through the cross section of the workpiece with a speed corresponding to the condition of the fly-cutting, the speeds of rotation of tool holder and workpiece being in a ratio determined by the desired profiled structure.
Such a fly-cutter milling machine is known from U.S. Pat. No. 4,141,278, the axis of rotation of the workpiece and the axis of the tool holder being arranged axially parallel to each other. In order, for instance, to be able to mill a quadratic polygon on a cylindrical workpiece, the tool holder must be provided with two diametrically opposite outwardly protruding fly cutters. Each of these fly cutters then cuts two polygonal surfaces of the polygon which are parallel to each other. In order that these surfaces are not barreled but flat, a speed rotation ratio between the tool holder and the workpiece of 2:1 is necessary. A hexagon similarly requires three fly-cutters arranged at equal circumferential distances apart on the tool holder. As a result of this step-up ratio of 2:1 it is not possible to produce a polygon having an odd number of corners unless the speed ratio is changed and a barreled surface is tolerated. Thus only surfaces which are parallel to each other can be worked by a single fly-cutter into a cylindrical workpiece. In order that the fly cutter milling machine operate economically, it is necessary to work with high speeds of rotation. However this is limited by the nature of the fly cutter itself.
A fly cutter milling machine is also known from Federal Republic of Germany OS 1 921 514, the tool holder axis and the workpiece axis of rotation being arranged at right angles and skew to each other. In this way it is possible to produce grooves spaced equally apart on the periphery on the workpiece with high cutting speed without use of a coolant, due to the free-cutting of the tool cutting edge. In this case the grooves extend in the axial direction of the workpiece. Helical grooves cannot be produced with this flycutter milling machine. By the free-cutting, the grooves are somewhat enlarged in their cross sectional shape as compared with the cutting profile of the fly cutter.